Air curtain for observation window



June 11, 1968 o. E. HUGHES 3,337,551

AIR CURTAIN FOR OBSERVATION WINDOW Filed July 22, 1966 2 mvzm'on 0A W0 5. HUG/1'55 BY @QMH 5%! ATTORNEYS United States Patent 3,387,551 AER CURTAEN FOR OBSERVATION WTNDOW David E. Hughes, La Vale, Md., assignor to Pittsburgh Plate Glass Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Juiy 22, 1966, Ser. No. 567,144 2 Claims. (Cl. 98-88) ABSTRACT OF THE DTSCLOSURE A window arrangement for a wall of a glass manufacturing apparatus is constructed so as to use a gas curtain to isolate the window from the atmosphere in the apparatus.

This invention relates to the manufacture of glass and especially to a viewing window construction for attachment to the wall of a glass manufacturing apparatus.

In the float process of manufacturing flat glass wherein glass is supported on a molten metal bath, the processing takes place under controlled conditions and in a closed space. To observe the process, viewing windows are provided in the walls of the float tank, -i.e., that tank which contains the molten bath.

The atmosphere Within such a tank is controlled and may contain constituents which will condense or be deposited on the inner face of a glass Window, rendering the window opaque and unusable within a short period of time. Replacement of the windows is thus frequently required, so as to observe the process, either by an operator or by a camera.

It has been proposed to provide a window structure in which a curtain of gas is moved across the interior of a box incorporating a window, as one side, in order to avoid the problems heretofore encountered and to isolate the window from the atmosphere within the tank.

The present invention is an improved construction of such a Window, as will be evident from the foregoing description taken with the accompanying drawing, in which FIG. 1 is a perspective view of a window arrangement constructed in accordance With this invention, and

FIG. 2 is a cross-sectional View of the apparatus of FIG. 1, taken on line 2-2 thereof.

In the drawing, the apparatus of this invention includes a rectangular frame having one end attached to the wall 12 of a float tank by any suitable means and in alignment with an opening 16 in the Wall 12. The opening 16 is, of course, above the float bath in the tank.

A frame box 18 is connected, as by welding, to the frame 10 and its outer end is sealed by a window 20- of glass. Generally, it is preferred to use tempered or wire glass for the window 20.

In the top 22 of the box frame 18, there is provided an elongated, relatively narrow slot 24 which extends from side wall to side wall of the frame 18 and a tapered manifold 26 is connected in registry with the slot, which manifold is connected to a source of controlled atmosphere, generally the same atmosphere supplied to the interior of the float tank. The tapered manifold 26 and the width of the slot 24 insure an even flow of atmosphere from top to bottom of the apparatus and across the window 2i).

To exhaust the supplied atmosphere there is provided an elongated relatively narrow slot 28 in the bottom wall 30 of the frame 18 opposite the intake slot 24. Usually the slot 28 is wider than the slot 24 to insure flow of atmosphere which may expand while in the frame 18 due to the temperature therein. A V-tapered manifold 32 is connected to the wall 30 in registry with the slot 28 to exhaust the amosphere from the frame 18. A discharge pipe 34 is connected to the manifold 32 and, in turn, is connected to a venturi device 36 connected in a supply line 38 of controlled atmosphere. The venturi device 36 insures a reduced pressure at the slot 28 and the flow of atmopshere across the window 20-. The atmosphere for the window can be, especially for economy reasons, recirculated. The pressure of the atmosphere supplied and withdrawn must be such to insure fiow across the window and not how into the float tank or from the float tank.

The device described can also be used in other equipment, such as glass melting tanks, or Where similar conditions are encountered. Also, other means, such as suction pumps, etc., can be used for exhausting the atmosphere from the frame 18.

I claim:

1. A window arrangement for connection to a wall of glass manufacturing apparatus having at least one openin g therein which comprises a frame fitted in registry with said opening, a glass window sealing the outer end of the frame, a slot in the top of the frame extending from side to side thereof, means connected to said slot for supplying a gas thereto and thus to said frame, a slot in the bottom of said frame extending from side to side thereof, means including a venturi-device connected to said second-named slot for withdrawing said gas, said slots directing gas supplied to said frame as a curtain across said window to isolate said window from the atmosphere in said glass manufacturing apparatus.

2. Apparatus as recited in claim. 1, further including a tapered manifold to insure uniform flow of gas to said first-named slot.

References (Iited UNITED STATES PATENTS 2,977,636 4/1961 Stout 98-436 X 2,896,854 7/1959 Noble et a1 9836 X 3,282,193 11/1966 Jennings 9836 ROBERT A; OLEARY, Primary Examiner.

W. E. WAYNER, Assistant Examiner. 

